From d8dfaf68948ea2c33de2d4fefe904bab6e636d6b Mon Sep 17 00:00:00 2001
From: Chris Penner <christopher.penner@gmail.com>
Date: Mon, 6 Dec 2021 15:49:02 -0600
Subject: [PATCH] Consider only head when checking for empty branch in most
 commands

---
 .../src/Unison/Codebase/Editor/HandleInput.hs | 10 +--
 .../transcripts/empty-namespaces.output.md    | 66 +++++--------------
 2 files changed, 21 insertions(+), 55 deletions(-)

diff --git a/unison-cli/src/Unison/Codebase/Editor/HandleInput.hs b/unison-cli/src/Unison/Codebase/Editor/HandleInput.hs
index 85bc5d1ed..53efd57fe 100644
--- a/unison-cli/src/Unison/Codebase/Editor/HandleInput.hs
+++ b/unison-cli/src/Unison/Codebase/Editor/HandleInput.hs
@@ -660,7 +660,7 @@ loop = do
                     let dest = resolveToAbsolute dest0
                     -- if dest isn't empty: leave dest unchanged, and complain.
                     destb <- getAt dest
-                    if Branch.isEmpty destb
+                    if Branch.isEmpty0 (Branch.head destb)
                       then do
                         ok <- updateAtM dest (const $ pure srcb)
                         if ok then success else respond $ BranchEmpty src0
@@ -677,7 +677,7 @@ loop = do
             MergeLocalBranchI src0 dest0 mergeMode -> do
               let [src, dest] = resolveToAbsolute <$> [src0, dest0]
               srcb <- getAt src
-              if Branch.isEmpty srcb
+              if Branch.isEmpty0 (Branch.head srcb)
                 then branchNotFound src0
                 else do
                   let err = Just $ MergeAlreadyUpToDate src0 dest0
@@ -685,7 +685,7 @@ loop = do
             PreviewMergeLocalBranchI src0 dest0 -> do
               let [src, dest] = resolveToAbsolute <$> [src0, dest0]
               srcb <- getAt src
-              if Branch.isEmpty srcb
+              if Branch.isEmpty0 (Branch.head srcb)
                 then branchNotFound src0
                 else do
                   destb <- getAt dest
@@ -1903,8 +1903,8 @@ doPushRemoteBranch repo localPath syncMode remoteTarget = do
     shouldPushTo :: PushBehavior -> Branch m -> Bool
     shouldPushTo pushBehavior remoteBranch =
       case pushBehavior of
-        PushBehavior.RequireEmpty -> Branch.isEmpty remoteBranch
-        PushBehavior.RequireNonEmpty -> not (Branch.isEmpty remoteBranch)
+        PushBehavior.RequireEmpty -> Branch.isEmpty0 (Branch.head remoteBranch)
+        PushBehavior.RequireNonEmpty -> not (Branch.isEmpty0 (Branch.head remoteBranch))
 
 -- | Handle a @ShowDefinitionI@ input command, i.e. `view` or `edit`.
 handleShowDefinition ::
diff --git a/unison-src/transcripts/empty-namespaces.output.md b/unison-src/transcripts/empty-namespaces.output.md
index f6c20757a..e617c22ba 100644
--- a/unison-src/transcripts/empty-namespaces.output.md
+++ b/unison-src/transcripts/empty-namespaces.output.md
@@ -1,75 +1,41 @@
 # Empty namespace behaviours
 
+## Operations on empty namespaces
+
+Add and then delete a term to add some history to a deleted namespace.
+
 ```unison
-mynamespace.x = 1
+deleted.x = 1
+stuff.thing = 2
 ```
 
-The deleted namespace shouldn't appear in `ls` output.
-```ucm
-.> ls
+I should be allowed to fork over a deleted namespace
 
-  nothing to show
+```ucm
+.> fork stuff deleted
+
+  Done.
 
 ```
-```ucm
-.> ls.verbose
-
-  😶
-  
-  No results. Check your spelling, or try using tab completion
-  to supply command arguments.
-
-```
-```ucm
-.> find mynamespace
-
-  😶
-  
-  No results. Check your spelling, or try using tab completion
-  to supply command arguments.
-
-```
-The history of the namespace should still exist if requested explicitly.
+The history from the `deleted` namespace should have been overwritten by the history from `stuff`.
 
 ```ucm
-.> history mynamespace
+.> history stuff
 
   Note: The most recent namespace hash is immediately below this
         message.
   
-  ⊙ #qjc20aua9h
   
-    - Deletes:
-    
-      x
   
-  □ #hkrqt3tm05 (start of history)
+  □ #3bm1524lb7 (start of history)
 
-```
-Merging an empty namespace should still copy its history if it has some.
-
-```ucm
-  ☝️  The namespace .empty is empty.
-
-.empty> history
-
-  ☝️  The namespace .empty is empty.
-
-.empty> merge .mynamespace
-
-  Nothing changed as a result of the merge.
-
-.empty> history
+.> history deleted
 
   Note: The most recent namespace hash is immediately below this
         message.
   
-  ⊙ #qjc20aua9h
   
-    - Deletes:
-    
-      x
   
-  □ #hkrqt3tm05 (start of history)
+  □ #3bm1524lb7 (start of history)
 
 ```